d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Whitespace cleanup for ipfw.8 -- start each sentence on a new line,

Browse Source 
and put a comma after e.g. and i.e..  While here, wrap long lines.

PR:		docs/157452
Approved by:	hrs (mentor)
This commit is contained in:
Benjamin Kaduk 2012-09-18 02:33:23 +00:00
parent 08466b02d4
commit 3a99e819f3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=240628
1 changed files with 58 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

91
sbin/ipfw/ipfw.8
View File

@ -141,7 +141,7 @@ the firewall will have a
.Em stateful
behaviour, i.e., upon a match it will create
.Em dynamic rules ,
i.e. rules that match packets with the same 5-tuple
i.e., rules that match packets with the same 5-tuple
(protocol, source and destination addresses and ports)
as the packet which caused their creation.
Dynamic rules, which have a limited lifetime, are checked
@ -223,14 +223,15 @@ When listing and
is specified, also show expired dynamic rules.
.It Fl f
Do not ask for confirmation for commands that can cause problems
if misused,
.No i.e. Cm flush .
if misused, i.e.,
.Cm flush .
If there is no tty associated with the process, this is implied.
.It Fl i
When listing a table (see the
.Sx LOOKUP TABLES
section below for more information on lookup tables), format values
as IP addresses. By default, values are shown as integers.
as IP addresses.
By default, values are shown as integers.
.It Fl n
Only check syntax of the command strings, without actually passing
them to the kernel.
@ -421,7 +422,7 @@ Keywords are case-sensitive, whereas arguments may
or may not be case-sensitive depending on their nature
(e.g.\& uid's are, hostnames are not).
.Pp
Some arguments (e.g. port or address lists) are comma-separated
Some arguments (e.g., port or address lists) are comma-separated
lists of values.
In this case, spaces after commas ',' are allowed to make
the line more readable.
@ -873,7 +874,8 @@ Takes rule number saved to internal stack by the last
action and returns ruleset processing to the first rule
with number greater than number of corresponding
.Cm call
rule. See description of the
rule.
See description of the
.Cm call
action for more details.
.Pp
@ -960,23 +962,29 @@ Initially this is limited to the values 0 through 15, see
Processing continues at the next rule.
It is possible to use the
.Cm tablearg
keyword with a setfib. If tablearg value is not within compiled FIB range packet fib is set to 0.
keyword with a setfib.
If tablearg value is not within compiled FIB range packet fib is set to 0.
.It Cm reass
Queue and reassemble ip fragments.
If the packet is not fragmented, counters are updated and processing continues with the next rule.
If the packet is not fragmented, counters are updated and
processing continues with the next rule.
If the packet is the last logical fragment, the packet is reassembled and, if
.Va net.inet.ip.fw.one_pass
is set to 0, processing continues with the next rule, else packet is allowed to pass and search terminates.
If the packet is a fragment in the middle, it is consumed and processing stops immediately.
is set to 0, processing continues with the next rule, else packet is
allowed to pass and search terminates.
If the packet is a fragment in the middle, it is consumed and
processing stops immediately.
.Pp
Fragments handling can be tuned via
.Va net.inet.ip.maxfragpackets
and
.Va net.inet.ip.maxfragsperpacket
which limit, respectively, the maximum number of processable fragments (default: 800) and
which limit, respectively, the maximum number of processable
fragments (default: 800) and
the maximum number of fragments per packet (default: 16).
.Pp
NOTA BENE: since fragments do not contain port numbers, they should be avoided with the
NOTA BENE: since fragments do not contain port numbers,
they should be avoided with the
.Nm reass
rule.
Alternatively, direction-based (like
@ -1596,7 +1604,8 @@ This is the short form of
.It Cm sockarg
Matches packets that are associated to a local socket and
for which the SO_USER_COOKIE socket option has been set
to a non-zero value. As a side effect, the value of the
to a non-zero value.
As a side effect, the value of the
option is made available as
.Cm tablearg
value, which in turn can be used as
@ -1746,7 +1755,7 @@ connected networks instead of all source addresses.
.El
.Sh LOOKUP TABLES
Lookup tables are useful to handle large sparse sets of
addresses or other search keys (e.g. ports, jail IDs, interface names).
addresses or other search keys (e.g., ports, jail IDs, interface names).
In the rest of this section we will use the term ``address''.
There may be up to 65535 different lookup tables, numbered 0 to 65534.
.Pp
@ -1784,7 +1793,8 @@ the routing table (see
.Xr route 4 ) .
.Pp
Lookup tables currently support only ports, jail IDs, IPv4/IPv6 addresses
and interface names. Wildcards is not supported for interface names.
and interface names.
Wildcards is not supported for interface names.
.Pp
The
.Cm tablearg
@ -1813,7 +1823,8 @@ Section for example usage of tables and the tablearg keyword.
When used with the
.Cm skipto
action, the user should be aware that the code will walk the ruleset
up to a rule equal to, or past, the given number, and should therefore try keep the
up to a rule equal to, or past, the given number,
and should therefore try keep the
ruleset compact between the skipto and the target rules.
.Sh SETS OF RULES
Each rule belongs to one of 32 different
@ -2021,10 +2032,12 @@ As an example, using ``src-ip 0xffffff00'' creates one instance
for each /24 destination subnet.
.Pp
The FLOW_MASK, together with the SCHED_MASK, is used to split
packets into flows. As an example, using
packets into flows.
As an example, using
``src-ip 0x000000ff''
together with the previous SCHED_MASK makes a flow for
each individual source address. In turn, flows for each /24
each individual source address.
In turn, flows for each /24
subnet will be sent to the same scheduler instance.
.Pp
The above diagram holds even for the
@ -2143,12 +2156,13 @@ A file specifying the additional overhead incurred in the transmission
of a packet on the link.
.Pp
Some link types introduce extra delays in the transmission
of a packet, e.g. because of MAC level framing, contention on
of a packet, e.g., because of MAC level framing, contention on
the use of the channel, MAC level retransmissions and so on.
From our point of view, the channel is effectively unavailable
for this extra time, which is constant or variable depending
on the link type. Additionally, packets may be dropped after this
time (e.g. on a wireless link after too many retransmissions).
on the link type.
Additionally, packets may be dropped after this
time (e.g., on a wireless link after too many retransmissions).
We can model the additional delay with an empirical curve
that represents its distribution.
.Bd -literal -offset indent
@ -2184,7 +2198,7 @@ If not specified here, it must be present
explicitly as a configuration parameter for the pipe;
.It Cm loss-level Ar L
the probability above which packets are lost.
(0.0 <= L <= 1.0, default 1.0 i.e. no loss);
(0.0 <= L <= 1.0, default 1.0 i.e., no loss);
.It Cm samples Ar N
the number of samples used in the internal
representation of the curve (2..1024; default 100);
@ -2249,7 +2263,8 @@ but gives no service guarantees.
.It Cm wf2q+
implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
algorithm which permits flows to share bandwidth according to
their weights. Note that weights are not priorities; even a flow
their weights.
Note that weights are not priorities; even a flow
with a minuscule weight will never starve.
WF2Q+ has O(log N) per-packet processing cost, where N is the number
of flows, and is the default algorithm used by previous versions
@ -2535,7 +2550,8 @@ in
.Xr natd 8
for more information.
.It Cm tablearg
Uses argument supplied in lookup table. See
Uses argument supplied in lookup table.
See
.Sx LOOKUP TABLES
section below for more information on lookup tables.
.El
@ -2597,11 +2613,13 @@ or
before ipfw module gets loaded.
.Bl -tag -width indent
.It Va net.inet.ip.fw.default_to_accept: No 0
Defines ipfw last rule behavior. This value overrides
Defines ipfw last rule behavior.
This value overrides
.Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
from kernel configuration file.
.It Va net.inet.ip.fw.tables_max: No 128
Defines number of tables available in ipfw. Number cannot exceed 65534.
Defines number of tables available in ipfw.
Number cannot exceed 65534.
.El
.Sh SYSCTL VARIABLES
A set of
@ -2631,12 +2649,14 @@ Option 1 should never be selected as this forms a security risk.
An attacker can
establish multiple fake associations by sending AddIP messages.
.It Va net.inet.ip.alias.sctp.chunk_proc_limit: No 5
Defines the maximum number of chunks in an SCTP packet that will be parsed for a
Defines the maximum number of chunks in an SCTP packet that will be
parsed for a
packet that matches an existing association.
This value is enforced to be greater or equal than
.Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
A high value is
a DoS risk yet setting too low a value may result in important control chunks in
a DoS risk yet setting too low a value may result in
important control chunks in
the packet not being located and parsed.
.It Va net.inet.ip.alias.sctp.error_on_ootb: No 1
Defines when the
@ -2658,7 +2678,8 @@ This value is only useful if the
.Nm nat
is tracking global IP addresses.
.It Cm 3
ErrorM is sent in response to all OOTB packets on both the local and global side
ErrorM is sent in response to all OOTB packets on both
the local and global side
(DoS risk).
.El
.Pp
@ -2709,12 +2730,14 @@ will only be an INIT or ASCONF-AddIP packet.
A higher value may become a DoS
risk as malformed packets can consume processing resources.
.It Va net.inet.ip.alias.sctp.param_proc_limit: No 25
Defines the maximum number of parameters within a chunk that will be parsed in a
Defines the maximum number of parameters within a chunk that will be
parsed in a
packet.
As for other similar sysctl variables, larger values pose a DoS risk.
.It Va net.inet.ip.alias.sctp.log_level: No 0
Level of detail in the system log messages (0 \- minimal, 1 \- event,
2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug). May be a good
2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
May be a good
option in high loss environments.
.It Va net.inet.ip.alias.sctp.shutdown_time: No 15
Timeout value while waiting for SHUTDOWN-COMPLETE.
@ -2733,7 +2756,8 @@ association is limited to this value
.El
.Pp
This variable is fully dynamic, the new value will be adopted for all newly
arriving associations, existing associations are treated as they were previously.
arriving associations, existing associations are treated
as they were previously.
Global tracking will decrease the number of collisions within the
.Nm nat
at a cost
@ -3280,7 +3304,8 @@ Some early work (1999-2000) on the
traffic shaper supported by Akamba Corp.
.Pp
The ipfw core (ipfw2) has been completely redesigned and
reimplemented by Luigi Rizzo in summer 2002. Further
reimplemented by Luigi Rizzo in summer 2002.
Further
actions and
options have been added by various developer over the years.
.Pp